Aimed primarily at a general readership and college students of biology, this book focuses on the question of how embryonic development changes in the course of evolution, thus giving rise to new types of creatures. It takes the view that biases in the ways that embryos can be altered are as important as natural selection in determining the directions that evolution has taken, including the one that led to the origin of humans.
Wallace Arthur is a Northern Irish evolutionary biologist, science writer, and Emeritus Professor of Zoology at the University of Galway. Educated at the University of Ulster and the University of Nottingham, he became known for interdisciplinary work linking evolution, ecology, and developmental biology. Arthur was among the founding editors of the journal Evolution & Development and has held visiting positions at Harvard University and Darwin College Cambridge. His research has focused on evo-devo, animal body plans, developmental bias, and arthropod segmentation. In later years he turned toward astrobiology and the possibility of extraterrestrial life, explored in books such as Parallel Worlds: Evolution of Life Across the Cosmos. He supports an expanded evolutionary synthesis incorporating advances in developmental biology.
With this book, the author attempts to bring aspects of the internal development of the body into the forefront of the evolutionary process. Arthur discusses that while natural selection, one of the most well-known evolutionary factor, is indeed a driving force in the process of evolution of organisms, the internal factors that affect the development of the body also play an important role of deciding in which way an organism will evolve.
The author even argues that Charles Darwin, the first scientist to put out the idea of natural selection in the context of evolution, also had the internally developmental factors in mind while introducing his ideas on evolution. By highlighting the various ways in which these developmental factors control and interact with the development of a given organism, Arthur concludes that a study that focuses on the combination of both the external influences (natural selection) and the internal factors (developmental components of an organism), often known as "Evolutionary developmental biology", will be a worthwhile endeavor.
Throughout the book, the author introduces and discusses interesting ideas in a language that is both engaging and accessible for laypeople outside of the field. I'd personally like to see more theoretical discussions on the idea of the evolutionary 3-D graph that analyzes the directions in which an organism can evolve. I also find the topic of determining the evolutionary tree from DNA data to be the most interesting, especially when the author makes the point that computer algorithms can be leveraged to process this data and output the tree that is the most probable.